Apparatus and method for bending glass using microwaves

ABSTRACT

An apparatus and method for bending glass substrate(s) are provided. Microwave radiation is used to heat glass substrate(s) for bending. As a result, a coating supported by the substrate(s) is not heated as much during the bending process compared to if only conventional IR radiation was used. Thus, more extreme degrees of glass bending may be achieved, and/or the likelihood of coating damage reduced.

[0001] This invention relates to an apparatus and method for heatbending glass sheets. More particularly, this invention relates to anapparatus and method for bending coated glass sheets by directingmicrowave radiation (waves) at the glass sheet(s) in order to heat thesame.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] Devices and methods for heat bending glass sheets are well knownin the art. For example, see U.S. Pat. Nos. 5,383,990; 6,318,125;6,158,247; and 5,443,669.

[0003]FIG. 1 is a schematic diagram illustrating a conventionalapparatus and method for heat bending glass sheets in making a laminatedproduct such as a vehicle windshield. Vehicle windshields are typicallycurved, and thus require first and second curved (as a result of heatbending) glass sheets laminated to one another via a polymer interlayer.First glass substrate 1 has a multi-layer solar control coating 3thereon (e.g., low-E coating 3 including at least one IR reflectinglayer of a material such as Ag); while second glass substrate 5 need notbe coated.

[0004] Referring to FIG. 1, two flat glass substrates 1, 5 are placed ina bending furnace (e.g., on a bending mold) in an overlapping manner byinterposing an optional lubricating powder (not shown) such as sodiumhydrogen carbonate, cerite, magnesium oxide, silica, or the like betweencontacting surfaces of the two glass substrates. The glass substrates 1,5 are then heated using infrared (IR) emitting heating elements 7 to aprocessing temperature(s) near a softening point of the glass (e.g.,from about 550 to 850 degrees C., more preferably from about 580 to 750degrees C.) in order to soften the overlapping glass substrates 1, 5.Upon softening, the glass substrates 1, 5 (including any solar controlcoating 3 thereon) are bent by their deadweight (i.e., sagging) along ashaping surface of a bending mold (not shown) into the desired curvedshape appropriate for the vehicle windshield being made. A press bendingapparatus (not shown) may optionally be used after the glass issufficiently softened (the press bending may be conducted as the finalstep before cooling the glass).

[0005] After being heat bent in such a manner, the bent glass substrates1, 5 (with solar control coating 3 still on substrate 1) are separatedfrom one another and a polymer inclusive interlayer sheet (e.g., PVB) isinterposed therebetween. The glass substrates 1, 5 are then laminated toone another via the polymer inclusive interlayer 9 in order to form theresulting vehicle windshield shown in FIG. 2.

[0006] Different vehicle windshield models require different shapes.Some shapes require more extensive bending (i.e., tighter/smaller radiiof curvature after bending) than others. As windshields requiringextensive/extreme bending are becoming more popular, the need for highperformance solar control coatings (e.g., including one or more IRreflecting Ag layers) has also increased. An example high performancesolar control coating 3 is disclosed in WO 02/04375 (and thuscounterpart U.S. Ser. No. 09/794,224, filed Feb. 28, 2001), both herebyincorporated herein by reference.

[0007] Unfortunately, it has been found that when using conventionalglass bending techniques, certain solar control coatings cannot on aregular basis withstand the bending process(es) sometimes used withoutsuffering damage, especially when very tight radius of curvature(s) arerequired for the windshield. For example, when using conventional IRheating techniques to bend glass sheets for a windshield when theaforesaid solar control coating is provided on one of the sheets, thetightest radius of curvature consistently achievable in the windshieldwithout coating damage is about 3,500 mm. However, windshields having asmaller (or more extreme) tightest radius of curvature are sometimesrequired, and thus cannot be consistently made using IR heatingtechniques without damaging the aforesaid coating. Set forth below is anexplanation as to why certain solar control coatings have a hard timewithstanding conventional IR heat bending processes without sufferingundesirable damage.

[0008] Referring to FIG. 1, conventional glass bending heating elementsemit IR radiation 8 in the near, mid and far IR ranges. By this we meanthat heating elements 7 emit each of near-IR (700-4,000 nm; or 0.7 to4.0 μm), mid-IR (4,000-8,000 nm; or 4-8 μm), and far-IR radiation. Muchof the IR radiation that reaches the glass to be bent is in the near-IRrange, as the peak of this IR radiation is often in the near-IR range.In certain example instances, at least about 50% of the IR radiationthat reaches the glass to be bent is in the near-IR range, sometimes 70%or higher.

[0009] As shown in FIG. 3, it has been found that typical soda limesilica glass (often used for substrates 1, 5) absorbs much incident IRradiation at wavelengths above about 3-4 μm (microns). FIG. 3 shows thatsoda lime silica glass is substantially opaque to IR radiation above 3-4μm, but rather transmissive of IR radiation below 3-4 μm. Unfortunately,this means that a significant amount of IR radiation in the near-IRrange (from 0.7 to 3-4 μm) is not absorbed by the glass substrate(s) 1and/or 5 and as a result passes therethrough and reaches solar controlcoating 3. As used herein, the phrase “from 0.7 to 3-4 μm” means from0.7 m to 3 and/or 4 μm.

[0010] Unfortunately, certain of this near-IR radiation which is notabsorbed by the glass substrate and reaches solar control coating 3, isabsorbed by the coating 3 (e.g., by Ag layer(s) of the coating) therebycausing the coating 3 to heat up. This problem (significant heating ofthe coating) is compounded by: (a) certain solar control coatings 3 havea room temperature absorption peak (e.g., of 20-30% or more) atwavelengths of approximately 1 μm in the near IR range, at whichwavelengths the underlying glass is substantially transmissive, and (b)the absorption of many solar control coatings 3 increases with a rise intemperature thereof (e.g., sheet resistance R_(s) of Ag layer(s)increase along with rises in temperature). In view of (a) and (b) above,it can be seen that the peak absorption of certain solar controlcoatings 3 at near-IR wavelengths of about 1 μm can increase from the20-30% range to the 40-60% range or higher when the coating temperatureincreases from room temperature to 500 degrees C. or higher, therebyenabling the coating to heat up very quickly when exposed to significantamounts of near-IR radiation.

[0011] Coating 3 is more susceptible to being damaged when it isunnecessarily heated up during the glass bending process. When coating 3is damaged, the bent glass substrate 1 with the damaged coating thereonis typically discarded and cannot be commercially used.

[0012] This problem (i.e., coating overheating) affects the shapes thatcan be attained in the bending process. In particular, more extremeglass bending requires more extreme heating (i.e., at highertemperatures and/or for longer times) of the glass to be bent. Asmentioned above, when the coating 3 of WO 02/04375 (and thus counterpartU.S. Ser. No. 09/794,224) is provided on one of the glass substrates (1or 5), the tightest radius of curvature of bent glass consistentlyachievable using conventional IR radiation to bend without damaging thecoating is about 3,500 mm. This is, or course, undesirable if a portionof a windshield is desired to have a tighter (smaller) radius ofcurvature; i.e., to be more bent.

[0013] U.S. Pat. No. 5,827,345 discloses the use of microwave energyduring the bending and tempering of glass. However, the '345 patent usesmicrowave energy solely for its heating speed. Thus, the '345 patentfails to recognize or solve the problem(s) (e.g., coating over-heatingand/or need for smaller radii of curvature(s) for bent glass) addressedand solved by the instant invention. In other words, the '345 patentfails to disclose or suggest using microwave radiation to heat coatedglass sheet(s) for the purpose of enabling the coated glass sheet(s) tobe bent to a more significant degree or smaller tightest radius ofcurvature.

[0014] An object of this invention is to minimize the peak temperatureattained (and/or the time at which a peak temperature is attained) by asolar control coating 3 during a process for heat bending a glasssubstrate that supports the coating.

[0015] Another object of this invention is to provide an apparatusand/or method for heat bending glass substrate(s)/sheet(s), theapparatus and/or method being designed to reduce the amount of near-IRradiation that reaches the glass substrate(s) to be bent during thebending process.

[0016] Another object of this invention is to provide a method and/orapparatus for heat bending coated glass substrate(s), where thesubstrate(s) is/are heated using at least microwave radiation. The useof microwave radiation (and/or less IR radiation) to heat the glassenables the solar control coating supported by the glass substrate toreach a lesser temperature and/or a maximum temperature for a lessertime period than if only conventional IR radiation was used for heating.

[0017] By reducing the maximum coating temperature and/or the time atwhich the coating realizes this temperature, certain embodiments of thisinvention can achieve one or more of the following advantages: (a) thesolar control coating is less likely to be damaged during the bendingprocess of an underlying glass substrate, (b) higher degrees of bending(i.e., tighter radii of curvature) of an underlying glass substrate(s)can be achieved without damaging the solar control coating; and/or (c)power consumption of the heater may possibly be reduced in certaininstances.

[0018] Another object of certain example embodiments of this inventionis to use microwave radiation to heat a coated glass substrate(s) duringa bending process, in order to enable the coated substrate to be bent soas to have a tightest radius of curvature of no greater than about 3,000mm, more preferably no greater than about 2,000 mm, and even morepreferably no greater than about 1,000 mm without significant coatingdamage. In certain example instances, the tightest radius of curvaturefor a windshield may be as low as 200-500 mm.

[0019] Another object of this invention is to fulfill one or more of theabove-listed objects.

[0020] In certain example embodiments of this invention, one or more ofthe above-listed objects is/are fulfilled by providing a method ofmaking a vehicle windshield, the method comprising: directing microwaveradiation toward first and second glass substrates in order to heat theglass substrates for bending, and wherein a coating supported by one ofthe glass substrates comprises at least one infrared (IR) reflectinglayer comprising silver (Ag) sandwiched between at least a pair ofdielectric layers; and bending the glass substrates and laminating thesubstrates together to form a vehicle windshield so that a tightestradius of curvature defined by a major surface of the resultingwindshield is no greater than about 3,000 mm.

[0021] In other embodiments of this invention, one or more of theabove-listed objects is/are fulfilled by providing a method of bendingcoated glass, the method comprising: directing microwave radiationtoward a glass substrate in order to heat the glass substrate forbending, and wherein a coating supported by the glass substratecomprises at least one infrared (IR) reflecting layer comprising silver(Ag) sandwiched between at least a pair of dielectric layers; andbending the glass substrate and the coating thereon so that a tightestradius of curvature defined by a major surface of the resulting bentglass substrate is no greater than about 3,000 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a schematic diagram of a conventional apparatus andmethod for bending glass sheets.

[0023]FIG. 2 is a cross sectional view of a vehicle windshield madeusing the apparatus and method of FIG. 1.

[0024]FIG. 3 is a graph (wavelength vs. absorption) illustrating theabsorption of IR radiation by a piece of soda lime silica glass as afunction of wavelength.

[0025]FIG. 4 is a schematic diagram illustrating an apparatus and methodfor bending glass substrate(s)/sheet(s) according to an exampleembodiment of this invention.

[0026]FIG. 5 is a flowchart illustrating certain steps taken in making avehicle windshield according to an example embodiment of this invention.

[0027]FIG. 6 is a cross sectional view of a vehicle windshield madeaccording to an example embodiment of this invention, wherein a tightestradius of curvature is illustrated for purposes of example only.

[0028]FIG. 7 is a cross sectional view illustrating an example low-Ecoating according to an embodiment of this invention that may beprovided on a glass substrate to be bent.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0029] Referring now more particularly to the accompanying drawings inwhich like reference numerals refer to like parts throughout the severalviews.

[0030]FIG. 4 is a schematic diagram of an apparatus and method forbending glass substrate(s)/sheet(s) according to an example embodimentof this invention. Glass sheets or substrates bent herein may be used inapplications such as vehicle windshields, other types of laminated ormonolithic windows, IG window units, or any other suitable application.

[0031] According to certain example embodiments of this invention, ithas surprisingly been found that the use of at least microwave energy toheat a coated glass substrate to be bent enables the glass substrate tobe bent while the maximum temperature achieved/realized (and/or the timeperiod for which a maximum temperature is achieved) by the coatingsupported by the substrate during the bending process is reduced. Byreducing the maximum temperature achieved by the coating during thebending process, the underlying substrate may be bent to a greaterextent and/or the likelihood of coating damage may be reduced.

[0032] In certain example embodiments of this invention, the microwaveradiation/energy used to heat the glass substrate(s) has a wavelength(s)(λ) of from about 1 to 11 mm, more preferably from about 2 to 10 mm,even more preferably from about 4 to 10 mm, and most preferably fromabout 6 to 10 mm. It has been found that wavelength(s) within the rangeof from about 6 to 10 mm work surprisingly well. Moreover, it has beenfound that when microwave radiation is used to heat a coated glasssubstrate for the purpose of bending the glass substrate, the coatingthereon does not absorb as much of the microwave radiation as comparedto conventional IR radiation. As a result, when microwave radiation isused to heat the glass substrate for bending, the coating is not heatedas much (as compared to when conventional IR is used to glass bending).Because the coating is not heated as much during the glass bendingprocess, tighter (i.e., smaller) radii of bending curvature for majorsurface(s) of the glass substrate can be achieved and/or there is lessof a chance for coating damage (e.g., Ag agglomeration) during thebending process.

[0033] Set forth below is an example of how glass may be bent usingmicrowave radiation according to certain example embodiments of thisinvention.

[0034] Referring to FIG. 4, first and second approximately flat glasssubstrates 1 and 5 are provided. First glass substrate 1 may have amulti-layer solar control coating 3 thereon (e.g., a low-E coatingincluding at least one IR reflecting layer of a material such as Ag,NiCr, Au or the like). Second glass substrate 5 may or may not be coatedin a similar manner. Coating 3 is provided on the side of substrate 1closest to the other substrate 5 in order to have the coating 3 betweenlites after lamination. The glass substrates 1, 5 may be of or includesoda lime silica glass, or any other suitable type of glass in differentembodiments of this invention.

[0035] Example solar control coatings 3 are disclosed in U.S. Ser. No.09/794,224 filed Feb. 28, 2001 (see WO 02/04375), and in U.S. Pat. Nos.5,229,194; 5,298,048; 5,557,462; 3,682,528; 4,898,790; 5,302,449;6,045,896; and 5,948,538, all hereby incorporated herein by reference.While these are examples of solar control coatings 3 which may be used,this invention is not so limited as any other suitable solar controlcoating may instead be used. In certain embodiments of this invention,solar control coating 3 includes at least one IR reflecting layer (e.g.Ag, Au or NiCr) sandwiched between at least first and second dielectriclayers (e.g., see FIG. 7). In certain embodiments, the solar controlcoating 3 includes first and second IR reflecting layers (e.g., of orincluding Ag, Au or the like), a first dielectric layer (e.g., of orincluding silicon nitride, silicon oxide, titanium oxide or the like)provided between the underlying glass substrate 1 and the first IRreflecting layer, a second dielectric layer provided between the two IRreflecting layers, and a third dielectric layer provided over both IRreflecting layers (e.g., see WO 02/04375 and Ser. No. 09/794,224) (e.g.,see FIG. 7). In certain embodiments of this invention, coating 3 may bedeposited onto glass substrate 1 in any suitable manner (e.g., viasputtering as described in any of the aforesaid patents/patentapplications).

[0036] Referring to FIG. 4 for example, approximately flat glasssubstrates 1 (with coating 3 thereon) and 5 may be placed in a bendingfurnace in an overlapping manner by interposing an optional lubricatingpowder (not shown) such as sodium hydrogen carbonate, cerite, magnesiumoxide, silica, or the like between contacting surfaces of the two glasssubstrates. Coating 3 is between the substrates, and supported bysubstrate 1 and/or 5. Heating element(s) 7 (e.g., above and/or below theglass substrates 1, 5) emit at least microwave radiation 15 toward theglass substrates 1, 5 in order to heat the same for purposes of bending.

[0037] The microwave radiation may or may not be supplemented with otherradiation type(s) (e.g., IR) in different embodiments of this invention.For example, IR radiation may be used to pre-heat the glass (one or bothsubstrates 1, 5) up to about 400 to 550 degrees C., and thereafter whenthe glass becomes a better microwave absorber at these heightenedtemperatures, the microwave energy is directed at the glass as discussedherein. In this regard, see the optional IR radiation source(s) shown inFIG. 4 that may be used for such glass preheating.

[0038] As discussed above, in certain example embodiments the microwaveradiation/energy 15 used to heat the glass substrate(s) may be of orinclude wavelength(s) (X) of from about 1 to 11 mm, more preferably fromabout 2 to 10 mm, even more preferably from about 4 to 10 mm, and mostpreferably from about 6 to 10 mm. In certain embodiments of thisinvention, substantially all radiation used for heating the glasssubstrate(s) is microwave radiation as described above. However, inalternative embodiments of this invention, at least about 20% (morepreferably at least about 40%, even more preferably at least about 60%,and most preferably at least about 75%) of the radiation used forheating the glass substrate(s) to be bent is microwave radiation asdescribed above, with the remainder being made up of other radiationtype(s) such as IR radiation.

[0039] In certain instances, a single microwave source (i.e., heatingelement) may be provided, and a beam emitted therefrom is can be splitinto first and second portions. The first microwave beam portion 15 canbe directed at the top substrate, while the second microwave beamportion 15 can be directed at the bottom substrate via mirror(s) or thelike. The microwave beam 15 directed toward the substrate(s) may be usedto scan the surface of the substrate(s) or flood the surface of thesubstrate(s) in either case (top and/or bottom). Alternatively, morethan one microwave source may be used.

[0040] Because of the reduced amount of IR radiation reaching glasssubstrates and/or coating 3 (due to the use of the microwaves), thecoating is not heated as much as it would have been if conventional IRheat had been used for heat bending. Stated another way, by heating theglass substrate(s) using microwave radiation, the coating 3 can be keptat a lower temperature and/or the time period that the coating is athigher temperatures can be reduced. The ability to keep coating 3 at alower temperature, for example, during bending of the underlying glasssubstrate 1 enables the coating 3 to be less susceptible to damage. As aresult, yields increase and/or more extreme bending may optionally beconducted.

[0041] During the bending process, the glass substrates 1, 5 are heatedusing microwave radiation to a processing temperature(s) near asoftening point of the glass (e.g., from about 550 to 850 degrees C.,more preferably from about 580 to 750 degrees C.) in order to soften theoverlapping glass substrates 1, 5. Upon softening, in certain exampleembodiments the glass substrates 1, 5 (including any solar controlcoating 3 thereon) are bent by their deadweight (i.e., sagging) along ashaping surface of a bending mold (not shown) or other suitablestructure into the desired curved shape. The glass sheets may optionallybe press bent after reaching an appropriate temperature. After beingheat bent in such a manner, the bent glass substrates 1, 5 (with solarcontrol coating 3 still on substrate 1) are separated from one anotherand a polymer inclusive interlayer sheet 9 (e.g., of or includingpolyvinyl butyral (PVB) or any other suitable laminating material) isinterposed therebetween. The bent glass substrates 1, 5 are thenlaminated to one another via at least the polymer inclusive interlayer 9in order to form a vehicle windshield W or any other suitable structure(e.g., see FIG. 2).

[0042] In certain example embodiments of this invention, the windshieldmay be bent to a more extreme degree (i.e., to a tighter or smallertightest radius of curvature) due to the use of the microwave radiationwhich allows the coating to absorb less heat during bending. Forexample, in certain embodiments the resulting windshield W may have atightest (smallest) radius of curvature of no greater than about 3,000mm, more preferably no greater than about 2,000 mm, and even morepreferably no greater than about 1,000 mm without significant coatingdamage. In certain example instances, the tightest radius of curvaturefor the windshield W may be as low as 200-500 mm (e.g., see FIG. 6).Those skilled in the art will of course recognize that these radii ofcurvature are with respect to a major(s) surface of the windshield W (asopposed to the periphery of the windshield).

[0043] The phrase “tightest (or smallest) radius of curvature” means thesmallest radius of curvature defined for any portion of a major surfaceof the bent substrate or windshield. For example, consider a bentwindshield that has a curved major surface that defines may differentradii of curvature (i.e., the windshield is bent to different degrees atdifferent locations). The tightest radius of curvature is defined at theportion of the bent windshield (or coated substrate) that has the mostextreme bend (i.e., sharpest bend).

[0044] While FIG. 4 illustrates a pair of glass substrates 1, 5 beingbent together at the same time, certain embodiments of this inventionare not so limited. In certain alternative embodiments, the bendingapparatus may bend only one glass substrate at a time. Moreover, bendingtechniques and/or methods herein may be used to bend glass substrates 1,5 regardless of whether they have coatings thereon. The techniquesdescribed herein may also be used in order to temper glass substrates(instead of or in addition to bending the glass).

[0045] The aforesaid embodiments illustrate first and second heatingelements provided on the top and bottom sides, respectively, of glass tobe bent. However, this invention is not so limited in all embodiments,as in certain embodiments of this invention only a single heatingelement need by provided (either above or below the glass to be bent).

[0046]FIG. 5 is a flowchart illustrating an example embodiment of thisinvention where microwave radiation is used in bending a pair ofsubstrates (one coated, the other not coated with a low-E coating) inmaking a vehicle windshield. In particular, the outer glass sheet 1 hasa coating 3 thereon, while the inner glass sheet 5 does not. The outerglass sheet is coated with coating 3, cut into a desired windshieldshape, and optionally seamed/washed and/or dried. The inner glass sheetis optionally washed and dried, and then an opaque frit layer may beapplied around a peripheral area thereof. The frit layer is cured andcooled. The inner glass sheet is then cut into the desired windshieldshape, and optionally seamed, washed and/or dried. The two glass sheetsare then booked, optionally with a separator powder therebetween. Thebooked glass sheets/substrates are then heat bent using microwave energyas discussed above. After being bent together in the same furnace, thebent glass sheets are laminated to one another via at least a polymerinclusive interlayer 9 to form a vehicle windshield.

[0047] An example non-limiting low-E coating 3 is shown in FIG. 7. Theexample coating 3 includes, from the glass substrate 1 outwardly, adielectric layer (e.g., an oxide of titanium, or any other suitabledielectric), another dielectric layer (a nitride of silicon, or anyother suitable dielectric), a first contact layer (e.g., NiCrO_(x) orany other suitable layer for contacting Ag), a first IR reflecting layer(e.g., Ag or the like), a second contact layer (e.g., NiCrO_(x) or anyother suitable layer for contacting Ag), another dielectric layer (e.g.,tin oxide, or any other suitable dielectric), another dielectric layer(e.g., a nitride of silicon, or any other suitable dielectric), a thirdcontact layer (e.g., NiCrO_(x) or any other suitable layer forcontacting Ag), a second IR reflecting layer (e.g., Ag or the like), afourth contact layer (e.g., NiCrO_(x) or any other suitable layer forcontacting Ag), another dielectric layer (e.g., tin oxide, or any othersuitable dielectric), and finally a top dielectric layer (e.g., anitride of silicon, or any other suitable dielectric). Optionally,certain layers may be added or deleted as desired. In certainalternative embodiments, a protective layer comprising diamond-likecarbon (DLC) may be provided over the top of coating 3. As discussedabove, other types of coatings may instead be used.

[0048] Moreover, it is noted that the coating 3 may be provided oneither of the two substrates in different embodiments. Moreover, itwould be possible to provide a coating on both substrates in certaininstances.

[0049] While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. An apparatus for bending coated glass, the apparatus comprising: atleast one source for directing microwave radiation toward a glasssubstrate in order to heat the glass substrate for bending, wherein acoating supported by the glass substrate comprises at least one infrared(IR) reflecting layer comprising silver (Ag) sandwiched between at leasta pair of dielectric layers; and means for bending the heated glasssubstrate and the coating thereon so that a smallest radius of curvaturedefined by a major surface of the resulting bent glass substrate is nogreater than about 3,000 mm.
 2. The apparatus of claim 1, wherein theglass substrate is bent so that the smallest radius of curvature definedby the bent glass substrate is no greater than about 2,000 mm.
 3. Theapparatus of claim 1, wherein the glass substrate is bent so that thesmallest radius of curvature defined by the bent glass substrate is nogreater than about 1,000 mm.
 4. The apparatus of claim 1, wherein themicrowave radiation comprises wavelength(s) within a range of from about6 to 10 mm.
 5. The apparatus of claim 1, wherein the microwave radiationconsists essentially of wavelength(s) within a range of from about 6 to10 mm.
 6. The apparatus of claim 1, wherein the coating comprises firstand second IR reflecting layers each comprising Ag, and at least onedielectric layer provided between the first and second IR reflectinglayers.
 7. A method of bending coated glass, the method comprising:directing microwave radiation toward a glass substrate in order to heatthe glass substrate for bending, wherein a coating supported by theglass substrate comprises at least one infrared (IR) reflecting layercomprising silver (Ag) sandwiched between at least a pair of dielectriclayers; and bending the glass substrate and the coating thereon so thata tightest radius of curvature defined by a major surface of theresulting bent glass substrate is no greater than about 3,000 mm.
 8. Themethod of claim 7, wherein the glass substrate is bent so that thetightest radius of curvature defined by the bent glass substrate is nogreater than about 2,000 mm.
 9. The method of claim 7, wherein the glasssubstrate is bent so that the tightest radius of curvature defined bythe bent glass substrate is no greater than about 1,000 mm.
 10. Themethod of claim 7, wherein the microwave radiation compriseswavelength(s) within a range of from about 6 to 10 mm.
 11. The method ofclaim 7, wherein the microwave radiation consists essentially ofwavelength(s) within a range of from about 6 to 10 mm.
 12. A method ofmaking a vehicle windshield, the method comprising: directing microwaveradiation toward first and second glass substrates in order to heat theglass substrates for bending, providing a coating supported by one ofthe glass substrates which comprises at least one infrared (IR)reflecting layer comprising silver (Ag) sandwiched between at least apair of dielectric layers; and bending the glass substrates andlaminating the substrates together to form a vehicle windshield so thata tightest radius of curvature defined by a major surface of theresulting windshield is no greater than about 3,000 mm.
 13. The methodof claim 12, wherein the glass substrates are bent so that the tightestradius of curvature defined by the windshield is no greater than about2,000 mm.
 14. The method of claim 12, wherein the glass substrates arebent so that the tightest radius of curvature defined by the windshieldis no greater than about 1,000 mm.
 15. The method of claim 12, whereinthe microwave radiation comprises wavelength(s) within a range of fromabout 6 to 10 mm.
 16. The method of claim 12, wherein the microwaveradiation consists essentially of wavelength(s) within a range of fromabout 6 to 10 mm.
 17. A method of bending coated glass, the methodcomprising: directing microwave radiation toward a glass substrate inorder to heat the glass substrate for bending; and bending the glasssubstrate so that a smallest radius of curvature defined by a majorsurface of the resulting bent glass substrate is no greater than about3,000 mm.
 18. A method of making a vehicle windshield, the methodcomprising: directing microwave radiation comprising at least onewavelength from 6 to 10 mm toward a glass substrate in order to heat theglass substrate for bending; providing a coating on the glass substrateto be bent, the coating comprising at least one layer comprising Agsandwiched between at least two dielectric layers; and after heating theglass substrate using the microwave radiation, causing the glasssubstrate to be bent and thereafter laminated to another substratethereby forming a vehicle windshield.
 19. The apparatus of claim 1,further comprising an IR radiation source for pre-heating at least oneof the glass substrates to about 400 to 550 degrees C., and thereafterusing the microwave energy to increase the temperature of the glasssubstrate(s) to bending temperature(s).
 20. The method of claim 7,further comprising direction IR radiation toward the glass substrate inorder to pre-heat the substrate to a temperature of from about 400 to550 degrees C., and thereafter using the microwave radiation to furtherheat the glass substrate for bending.